The problem with gmail's OAuth is the initial setup. After that is done, it works fine for years. First, you need to create an authorization token and a refresh

The problem with gmail's OAuth is the initial setup. After that is done, it works fine for years. First, you need to create an authorization token and a refresh token. If your authorization fails, you need to use your refresh token to get a new key. But the most damning part is: The initial process which gets you a refresh token requires you to login via browser. That's hard to deploy on a headless server. At some point I remember having to create a large enough swap space to run UI, install xorg, install google-chrome, go through the graphical process, then uninstall xorg and remove the unused swap.